Electromagnetic actuating apparatus with the armature and pole pieces having corresponding surfaces in continuous rolling contact



Nov. 4. 1969 A. KREIDLER 3,477,049

ELECTROMAGNETIC ACTUATING APPARATUS WITH THE ARMATURE AND POLE PIECESHAVING CORRESPONDING SURFACES IN CONTINUOUS ROLLING CONTACT Filed June15, 1967 6 Sheets-Sheet 1 FIG. 7

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Nov. 4, 1969 A. KREIDLER 3,477,049

I ELECTROMAGNETIC ACTUATING APPARATUS WITH THE ARMATURE AND POLE PIECESHAVING CORRESPONDING SURFACES IN CONTINUOUS ROLLING CONTACT Filed. June15, 1967 6 Sheets-Sheet 2 fivvzvrae '44 A 50 (Q5/045 Nov. 4, 1969 A.KREIDLER 3,477,049

ELECTROMAGNETIC ACTUATING APPARATUS WITH THE ARMATURE AND POLE PIECESHAVING CORRESPONDING SURFACES IN CONTINUOUS ROLLING CONTACT Filed June15, 1967 V 6 Sheets-Sheet 3 v FIG. 4

fivyzvroe. 14/ 50 fizmzz/g Nov. 4, 1969' A. KREIDLER 3,477,049

ELECTROMAGNETIC ACTUAT ING APPARATUS WITH THE ARMATURE AND POLE PIECESHAVING" CORRESPONDING SURFACES IN CONTINUOUS ROLLING CONTACT Filed June15, 1967 I 6 Sheets-Sheet 4 FIG. 7

Ax Va/rae 40- 50 flea/p4 a Nov. 4, 1969 A. KREIDLER 3,477,049

ELECTROMAGNETIC ACTUATING APPARATUS WITH THE ARMATURE AND POLE PIECESHAVING CORRESPONDING SURFACES IN CONTINUOUS ROLLING CONTACT Filed June3.5, 1967 6 Sheets-Sheet 5 hazy/we. firgzo (fez/[145g NOV. 4, 1969KRElDLER 3,477,049

ELECTROMAGNETIC ACTUATINC APPARATUS WITH THE ARMATURE AND POLE PIECESHAVING CORRESPONDING SURFACES IN CONTINUOUS ROLLING CONTACT Filed June15, 1967 6 Sheets-Sheet 6 FIG. 73

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United States Patent US. Cl. 335-276 8 Claims ABSTRACT OF THE DISCLOSUREAn electromagnetic actuating apparatus in which an armature is attractedby an electromagnet when current is switched on. This kind of apparatusis employed for actuating electric switches, such as clockwork windersor the like. The armature rolls upon the pole piece in continuousrolling contact so as to reduce noise of operation.

This invention relates to an electromagnet actuating apparatus in whichan armature is attracted by an electromagnet when current is switchedon. This kind of apparatus is employed for actuating electric switches,such as clockwork winders or the like.

Striking of the armature upon the pole piece of an electromagnet resultsin a brief impact noise which is undesirable in many cases. Variousmeasures are known whose purpose is to eliminate or at least to reducethe aforementioned impact noise. It has been proposed to dispose anintermediate layer of damping material, such as foam rubber, between thearmature and the pole piece. Quite apart from the fact that suchmeasures can only reduce but not completely eliminate the noise, suchdamping suifers from the disadvantage of substantially weakening theforce effect of the magnet because, owing to the presence of the dampingmaterial, a gap of considerable size remains between the armature andpole piece. It is also known to swing the armature past the pole pieceof the electromagnet perpendicularly to its axis. Although thisprocedure is completely free of noise, it necessitates an air gap ofconsiderable size between armature and pole piece which in turn resultsin a considerable deterioration of the force effect.

The invention provides a remedy and enables the deliberate strikingnoise to be entirely avoided without incurring any new disadvantages.The solution to the problem is obtained in an electromagnetic actuatingapparatus of the kind heretofore described by constructing the armatureas a member which rolls upon the pole piece of the electromagnet. It isappropriate for the armature and pole piece to be in physical contact inthe quiescent condition at the starting position of the rolling motion.

Two different basic armature forms are possible: the armature may beconstructed as rigid member whose shape and method of guiding permitsrolling upon a pole piece. Alternatively, the armature may beconstructed as a resilient strip adapted for progressive bearing uponthe pole piece.

Based upon the foregoing, it is possible to devise a plurality ofembodiments of the invention which attain the still further objects andfeatures which will become apparent as the following descriptionproceeds, the embodiments being shown by way of example only, wherein.

3,477,049 Patented Nov. 4, 1969 FIG. 1 is a sectional detail view of thedevice provided with a solenoid core having a planar end face and acurved armature and provided with a tension spring;

FIG. 2. is a view similar to FIG. 1 of an embodiment employing anon-magnetic spring;

FIG. 3 is a sectional detail view of an embodiment of the inventionemploying a solenoid core having a convex end face and a straightarmature;

FIG. 3a is a schematic illustration of an embodiment of the inventionemploying a solenoid core with a convex end face, a straight armature,and a clock winder mechamsrn;

FIG. 4 is a sectional detail view of an embodiment provided with aconvex end face for the solenoid core and an arcuate armature;

FIG. 5 is a sectional detail view of a further embodiment provided witha linkage mechanism;

FIG. 6 is a sectional detail view illustrating an arrangement of anarcuate spring disposed between the solenoid core and the armature;

FIG. 7 is an illustration showing parts in section of an arrangementwherein the solenoid core and the armature are provided withcomplementary interengaging teeth;

FIGS. 7 and 8a are schematic diagrams of an arrangement employing anarcuate pole piece having portions of differing curvatures;

FIG. 9 is a sectional detail view illustrating an embodiment of theinvention including a solenoid core provided with a convex face andemploying a resilient straight armature;

FIG. 10 is a schematic illustration of an arrangement similar to FIG. 9employing a resilient curved armature;

FIG. 11 is a schematic illustration of an arrangement wherein thesolenoid core is planar and a resilient armature is curved;

FIG. 12 is a sectional detail view illustrating a modification of theinvention employing a resilient strip armature mounted in a pivotedcradle;

FIG. 13 is a sectional detail view of an embodiment of the inventionhaving a strip armature of non-magnetic material provided with soft ironpieces thereon;

FIG. 14 is a partial enlarged plan view of the strip armature shown inFIG. 3.

FIG. 14a is a partial plan view of a modified form of a strip armature;

FIG. 15 is a partial plan view of a modified form of a strip armaturehaving soft iron members disposed between two non-magnetic strips; and

FIG. 15a is a longitudinal sectional view of the strip armature shown inFIG. 15.

With continuing reference to the accompanying drawings wherein likereference numerals designate similar parts throughout the various views,reference numeral 1 designates the solenoid core of a cup magnetutilized in the various embodiments of the invention. The solenoid coreis disposed centrally in a cup structure 2 and is joined to its base.The cup 2 and core 1 are constructed of magnetizable material, mainlysoft iron. A winding 3 in the cup 2 surrounds the solenoid core 1.

As shown in FIG. 1, the pole piece 4 formed by the end face of the cup 2together with the end face of the solenoid core 1 is constructed inplanar form. The armature 5 on the other hand is curved. It is retainedin its initial or starting position by a tension spring 6 while touchingthe pole piece 4 at a tangential position 7 and bearing on its otherside upon a stop 8. A further stop 9 limits the rolling motion resultingfrom the magnet action in the attracted position of the armature 5. Apivoting eye for the mechanism to be actuated is provided at that end ofthe armature 5 which faces away from the operating position of thetension spring 6.

FIG. 2 illustrates an arrangement similar to FIG. 1 wherein the tensionspring and the stop are replaced by a shaped spring 11 of non-magneticmaterial. The non-magnetic material may be, for example, bronze.

The spring 11 at the same time serves for guiding and resetting of thearmature 5 and is secured directly to the cup 2.

The example illustrated in FIG. 3 diifers from that illustrated in FIG.1 only in that a plane or straight armature 12 cooperates with a polepiece 13, of the solenoid core 2, having a convex curvature.

FIG. 3a illustrates schematically an embodiment of the device shown inFIG. 3 with the principal parts of a clockwork associated therewith. Acontact roll 54 is located at the free end of the armature 12. Thecontact roll 54 cooperates with the tensioning lever 55 which swivelsabout a shaft 56 of the ratchet gear 57. Tensioning lever 55 carries atone end thereof a flywheel mass 58 and at its other end a pawl 59 whichis provided with a leaf spring 66 and engages the teeth 61 of theratchet gear 57. A rigidly mounted stop 62 limits the swinging movementof tensioning lever 55 which is engaged by clock spring 63. The clockspring is shown diagrammatically as a helical tensioning spring for thesake of simplicity. The clockwork proper is indicated schematically bycircles 64 and 65. A battery 66 is connected with the coil 3 of themagnet through the conductor lead 67. Armature 12 is electricallyconnected through lead 68 and tensioning spring 6 and through contactroll 54 conductively engaging tensioning lever 55 in the position shown.The circuit to the battery 66 is closed over the clock spring 63 andconductor lead 69.

At the location shown, the electromagnet coil 3 is supplied withcurrent, the armature 12 is wound and the tensioning lever 55 swivelsover roll 54 of the armature in the direction of arrow a therebytensioning clock spring 63. When armature 12 comes to a standstill inthe position shown in phantom lines, the tensioning lever 55 still movesby a certain angle as a result of the inertia of its flywheel mass 58until it stops at the stop 62 indicated by the phantom line position oftensioning lever 55. In this position pawl 59 engages the teeth 61 ofthe wheel 57, thereby coupling the tensioned clock spring 63 with theclockwork 64, 65. As soon as the tensioning lever 55 has left contactroll 54, the magnet coil 3 becomes currentless. The armature 12 isbrought back by means of spring 6 into starting position and it remainsthere until the clockwork 64, 65 driven by spring 63 has run down andthe tensioning lever 55 again runs up against roll 54. With the currentconnection thus restored, the aforedescribed operation is repeated.

FIG. 4 illustrates an embodiment incorporating a pole piece 13 of convexcurvature which is engaged by an armature 14 having a concave curvatureof lesser concavity caused by a greater radius of curvature than thepole piece 13. A shaped spring 11 is also used for guiding andresetting.

The embodiment illustrated in FIG. 5 by contrast shows a plane polepiece 4 and an armature 15 having a convex configuration at whoseapproximate center there is an extending arm 16 mounted thereupon. Aguide rod 18 is pivotally connected to and acts upon the end of the arm16 at the pivot point located at the center of curvature 17 of thearmature 15. The rod 18 together with three rollers 19 located fixedlyrelative to the surrounding space provides appropriate rectilinearguiding for controlling movement of the pivot point 17. The motion ofthe guide rod 18 is limited by stops 20 and 20a. A helical tensionspring 21 is provided for resetting. An additional stop 22 is providedon the cup 2 for direct bearing thereon of the armature 15 in thestarting position.

The further example illustrated in FIG. 6 has a pole piece 23 of concavecurvature and an armature 24 of corresponding convex curvature but witha somewhat smaller radius of curvature. At its center of curvature 25the armature is hinged on a lug 26 which is pivotable about thestationary pivot 27 of the pole piece 23. A leaf spring 28 mounted onone side of the armature 24 near the starting position 7 of the rollingmotion and on the other side on a position 29 stationary relative to theambient space is provided for resetting and additional guiding. In orderto provide the least possible obstruction to the close bearing of thearmature 24 upon the pole piece 23 intended by the choice of similarcurvature radii, it is possible for a small groove 30 to be provided inthe armature for accommodating the leaf spring 28. The lug 26 inconjunction with the resetting spring 28 provides advantageous guidingfor the armature 24.

FIG. 7 represents a variation of the preceding embodiment but being noless advantageous. In this embodiment the pole piece 23 and the armature24 are provided with alternate teeth 31 and 32 which enmesh on rolling.A leaf spring 34 is provided for resetting into the starting positionlimited by a stop 33.

FIGURES 8 and 8a show in particular in the two limiting positions and toan enlarged scale the rolling surface of pole piece and armature of anembodiment representing an improvement relative to the exampleillustrated in FIG. 6. In this embodiment the rolling surface of thepole piece 23 is divided into two sections 35 and 36 of arcuate formwhile the rolling surface on the armature 24 represents a single sectionof arcuate configuration. The radius of curvature of the section 35disposed forwardly in the direction of the rolling motion is larger thanand the radius of curvature of the other section 36 is equal to theradius of curvature of the rolling surface of the armature 24. Asindicated in FIG. 8a, the armature 24 bears completely upon the innersection 36 when said armature is in the attracted position.

FIG. 9 represents a first example of an embodiment with an armatureconstructed as a resilient strip. 37. The strip 37 may be constructedfrom a resilient plastic material which has been rendered magnetizableby the insertion of soft iron particles. Its end 38 is secured to thecup 2 and is provided at its other end with an eyelet 39 for connectionto the mechanism to be actuated. In the static position the spring strip37 is straight. When current is switched on it bears upon the curvedpole piece 13 as indicated by the broken lines.

FIGS. 10 and 11 show two modifications. In the first of these the polepiece 13 is also curved and the spring strip 40 is pre-bent inapproximate adaption to the aforementioned curvature. In thelast-mentioned modification the pole piece 4 is planar and the springstrip 41 is curved away from the pole piece 4 when it is in its startingposition.

FIG. 12 illustrates an example in which the pole piece 13 is once againconstructed in curved form. The strip 42 is maintained tensioned in arigid cradle 44 by means of a resilient section 43, the cradle 44 beingpivoted by means of trunnions 45 on the bearing pedestal 46 so that saidstrip 42 touches the pole piece 13 at the starting position 7 of therolling motion. When current is switched on the strip 42 together withthe cradle 44 is attracted and bears resiliently and progressively uponthe pole piece 13. It is also possible to employ with advantage aflexible soft iron strip which is tensioned by a resilient cradle.

As shown in FIG. 13 the strip 47 may be constructed from a non-magneticresilient material. The strip 47 is preferably constructed of anon-magnetic metal and is provided with individual soft iron pieces 48disposed closer adjacently in line. A greater force effect is obtainedthereby when compared to a thin self-magnetiza'ble strip.

To increase the flexibility of the strip this may also be provided withrecesses 49 formed in the edge thereof.

5 This is illustrated in an enlarged scale in FIG. 14. A ladder strip inwhich webs 51 remain between recesses 50 as indicated in FIG. 14a servesthe same end.

FIGS. 15 and 15a illustrate an arrangement wherein a strip armature hassoft iron members 52 welded between two plastic strips 53.

A latitude of modification, substitution and change is intended in theforegoing disclosure, and in some instances, some features of theinvention will be employed without a corresponding use of otherfeatures. Accordingly, it is appropriate that the appended claims beconstrued broadly and in a manner consistent with the spirit and scopeof the invention herein.

I claim:

1. An electromagnetic actuating apparatus comprising an electromagnetincluding a solenoid core provided with a pole piece, and a movablearmature, said armature and said pole piece having correspondingsurfaces in continuous rolling contact, both of said correspondingsurfaces being curved, the radii of curvature of said correspondingsurfaces differing only slightly.

2. An apparatus according to claim 1, wherein the surface of said polepiece comprises two circular arcs of different radius, said surface ofthe armature is curved in a single circular arc, the radius of the partof the pole piece disposed forwardly in the direction of said continuousrolling contact being larger than the radius of curvature of thearmature, the radius of the adjacent curvature of the pole piece beingequal to the radius of curvature of the armature.

3. An electromagnetic actuating apparatus comprising an electromagnetincluding a solenoid core provided with a pole piece, and a movablearmature, said armature and said pole piece having correspondingsurfaces in continuous rolling contact, said pole piece and saidarmature being provided with complementary intermeshing teeth.

4. An electromagnetic actuating apparatus comprising an electromagnetincluding a solenoid core provided with a pole piece, and a movablearmature, said armature and said pole piece having correspondingsurfaces in continuous rolling contact, said armature being of aresilient strip for progressively bearing upon said pole piece, said 5strip being formed of a non-magnetic material, and a plurality ofdiscrete soft iron members bonded to said strip.

5. An apparatus according to claim 4, wherein said strip is providedwith recesses for increasing its flexibility.

6. An apparatus according to claim 5, wherein said pole piece has acurved surface.

7. An electromagnetic actuating apparatus comprising an electromagnetincluding a solenoid core provided with a pole piece, and a movablearmature, said armature and said pole piece having correspondingsurfaces in continuous rolling contact, said armature including a pairof resilient plastic strips, and a plurality of soft iron membersdisposed between and bonded to said strips.

8. An apparatus according to claim 1, wherein said armature and saidpole piece are in physical contact in the static condition at thestarting position of said continuous rolling contact.

References Cited UNITED STATES PATENTS 2,120,178 6/1938 Hausrath335--270 XR 3,051,988 9/ 1962. Baermann 335303 XR FOREIGN PATENTS688,832 6/1940 Germany.

G. HARRIS, Primary Examiner US. Cl. X.R. 335--279

